BA.3.2, an Omicron variant of Covid-19 with dozens of new spike mutations, has been detected in 29 US states and Puerto Rico, according to the Centers for Disease Control and Prevention, but experts say there is not yet evidence it is more severe than other recent variants.
“The right response to BA.3.2 is serious attention, not alarm,” says Dr Jake Scott, a Stanford professor and infectious disease expert who authored a systematic review of Covid vaccines for the New England Journal of Medicine.
“It’s a striking variant, with substantial changes in its spike protein, and it makes sense that the World Health Organization’s vaccine composition group has already flagged it for discussion at its May meeting,” Scott said, adding that WHO had classified BA.3.2 as a “variant under monitoring”, while thus far declining higher risk designations. In addition to vaccines, WHO recommends masking and improved ventilation in high-risk environments – to prevent all Covid-19 infections and related risks, such as long Covid.
Scott said that, according to WHO, “BA.3.2 has not shown a sustained growth advantage over any other co-circulating variant, and no data indicate increased severity, hospitalisations or deaths associated with this variant.” In the US, BA.3.2 still accounts for a low percentage of overall Covid-19 infections that have been analyzed, according to the CDC, but Scott said that, “in parts of Europe, it rose to a substantial share of sequenced cases without a clear signal of worse clinical outcomes.”
Marc Veldhoen, an immunologist at the University of Lisbon, agreed that in many ways, BA.3.2 was just a typical subvariant of Omicron: “This means biologically no major differences have been reported or are expected: it is Omicron Sars-CoV-2.” Symptoms are similar to those of other respiratory infections. While some media outlets have referred to BA.3.2 as a “highly” or “heavily” mutated variant, Veldhoen said that “heavily mutated is relative; Sars-CoV-2 is nearly 30,000 base pairs long.”
Current vaccines appear to be working as intended against the new variant, according to Veldhoen and Scott, although it is possible that the mutation will play a role in how next year’s vaccine is updated.
“The question that actually matters is whether BA.3.2 meaningfully erodes protection against severe disease,” said Scott, who added that as of now, all evidence shows that it doesn’t.
While Scott admitted that “antibodies that target the spike protein can lose some effectiveness when the virus changes significantly,” he noted that “vaccines and prior infection also build a deeper layer of immune memory, one that goes beyond antibodies and can recognize and fight the virus even after it has mutated.” That protection has been durable across variants, he said, “and it’s a major reason protection against hospitalization and death has remained more resilient than protection against infection”.
For the moment, public health officials, the general public and doctors do not need to change their behavior in response to this variant, Veldhoen said. Vaccine researchers, on the other hand, should be continuing to track the variant in order to determine how to best update the vaccine, Veldhoen added.
Scott acknowledged another concern some researchers have raised about BA.3.2. In the Global Initiative on Sharing All Influenza Data (Gisaid) database, which includes all reported sequencing data available on Covid-19, BA.3.2 is “overrepresented in pediatric samples relative to adults in several countries, and that pattern appears real”.
But Scott said he would “be cautious about the leap from ‘more commonly sequenced in children’ to ‘preferentially infects children’ in any clinically meaningful sense”.
Scott noted: “Sequencing data reflects who gets tested and whose samples get sequenced, not who actually gets infected.”
While adults with mild infections are less likely to get tested and have their results sequenced these days, children with symptoms are more likely to be tested, and seen in clinical settings where their virus will actually be sequenced. Another possibility that both Scott and Veldhoen noted is that children are more likely to be infected simply because they have less accumulated exposure than adults to different Covid-19 variants over the years.
“More importantly, there is no current signal that BA.3.2 is causing more severe disease in children,” Scott said, adding that until there was, the pattern was worth noting but not catastrophizing.
“The goal was never to prevent every infection. It was to keep people out of the hospital. That protection has proven more robust than the variant-by-variant headlines often suggest.”
